1. Field of Invention
Embodiments of the invention relate generally to methods and apparatuses that develop forces on a wing and, more specifically, to methods and apparatuses for generating lift utilizing oscillatory wing motions.
2. Art Background
Both fixed wing and rotary wing aircraft, such as airplanes and helicopters, employ fluid flow over a foil such as a wing or rotor, thereby producing the lift necessary to enable flight. Such flow occurs over a cambered surface at a relatively low angle of attack.
Fixed wing aircraft are able to fly at high speeds but require a runway in order to attain sufficient speed to create enough lift to become airborne. This can be a problem when it is desirable to operate such an aircraft on a runway of limited length. Also, it is difficult to build a fixed wing aircraft that can hover. One example is a Harrier Jet. Such a vertical takeoff jet requires a large amount of fuel to hover. The hover time is limited and a large amount of water is required to keep the jet engine cool during that time. Additionally, the surface of the ground beneath the jet during takeoff must be able to withstand the heat of the jet exhaust when the aircraft is executing a vertical takeoff. All of these aspects either singly or in combination may present a problem.
Rotary wing aircraft, on the other hand, are able to become airborne without a runway, yet these aircraft are unable to attain the high speeds of fixed wing aircraft. This may present a problem.
Rotary wing aircraft utilize a foil at a relatively low angle of attack to the flow and as the name “rotary” implies, constrain the foil to rotate about a fixed axis. Additionally, a rotary wing aircraft employs a tail rotor to prevent counter rotation of the vehicle. Such constraints of angle of attack, rotation of the foil about a fixed axis, tail rotor, etc. place design constraints on resulting vehicle designs that use a rotary foil. This may present a problem.